Mixed-function oxidases and esterases associated with cross-r esistance between DDT and lambda-cyhalothrin in Anopheles darlingi Root 1926 populations from Colombia

Abstract

In order to establish the insecticide susceptibility status for Enzyme levels related to insecticide resistance, including mixed function oxidases (MFO), non-specific esterases (NSE), glutathione S-transferases and modified acetylcholinesterase were evaluated in all populations and compared with a susceptible natural strain. Only mosquitoes from Amé-Beté presented significantly increased levels of both MFO and NSE, consistent with the low mortalities found in this population. The continued use of lambdacyhalothrin for An. darlingi control in this locality has resulted in a natural resistance to this insecticide. In addition, DDT resistance is still present in this population, although this insecticide has not been used in Colombia since 1992. Increased metabolism through MFO and NSE may be involved in cross-resistance between lambdacyhalothrin and DDT, although kdr-type nerve insensitivity cannot be discarded as a possible hypothesis. Additional research, including development of a kdr specific assay for An. darlingi should be conducted in future studies. Our data demonstrates the urgent need to develop local insecticide resistance management and surveillance programs throughout Colombia.Key words: insecticide resistance -bioassays -oxidases -esterases -Anopheles darlingi -Colombia Malaria is one of the major causes of morbidity and mortality worldwide. Nineteen countries in Latin America report active transmission of the disease, with one million clinical episodes annually. In addition, almost 250 million people are currently living in areas of risk for malarial infection (PAHO 2005). After Brazil, Colombia is the country with the highest index of malaria transmission in the Americas (WHO 2005a). Of all the cases that occurred during 2007, 27.5% were caused by Plasmodium falciparum. The zones of greatest transmission are located in the region of Bajo Cauca, Pacific Coast, the Valley of Sinú River and the region of Urabá (WHO 2005a, Sivigila 2007. In these areas, epidemic outbreaks are closely related with ecological imbalances and population displacement, resulted from the social situation in the country (WHO 2005b Although early diagnosis and treatment contributes to the prevention of malaria, control of vectors continues to be the most effective way of interrupting transmission in endemic areas. This measure of control is considered to be one of the four basic technical elements of the global strategy for malaria control (WHO 1993). Although vector control methods vary considerably in their applicability, costs and the reproducibility of results, there is a worldwide consensus for the use of indoor residual spraying (IRS) and insecticide treated nets (ITNs) with residual insecticides as major measures for the prevention of malaria. Both methods are effective in reducing the transmission of this disease through reducing the longevity of the vectors and decreasing human-vector contact (Lengeler & Sharp 2003).There are 45 Anopheles species documented in Colombia, but only seven are considered to be malaria vecto...

La Región “Urabá Antioqueño-Cuencas altas de los ríos Sinú y San Jorge-Bajo Cauca Antioqueño”: “guarida” del paludismo colombiano

“…Se ha informado en muy escasos y aislados tiempos y puntos, focalizada (probablemente debida al uso en la agricultura) [63][64][65][66][67] y de muy baja magnitud frente a los insecticidas de uso común en la lucha antimalárica 65,67 ; no obstante su escasez, esos datos siempre deben usarse para crear, desarrollar y operar sistemas de alerta temprana para evaluar el comportamiento de las casi cincuenta especies anofelinas en Colombia, de las cuales siete son consideradas vectores de Plasmodium, 65,66 como debe hacerse también con la vigilancia de la resistencia a los medicamentos. …”

Microgeographic Genetic Variation of the Malaria Vector Anopheles darlingi Root (Diptera: Culicidae) from Córdoba and Antioquia, Colombia

“…29,30 For many years, insecticidal control has been used as an important tool to decrease vector densities in different states in Colombia. 34,35 36 For MS analysis, specimens collected from VAL (n = 2) were not genotyped and specimens from ZAR (n = 8) that were genotyped were combined with samples from BAG whenever comparisons of population pairs were performed because otherwise the small sample size would not enable calculation of reliable results. For white and COI genes, all samples available per site or those randomly selected were analyzed ( Table 1 ).…”

Optimizing Strategic Insecticide Resistance Management Planning in Malaria Vectors

“…In An. darlingi, both multi-function oxidase (MFO)-and non-specific esterase (NSE)-based metabolic resistance were reported in a deltamethrin and DDT-resistant population [149]. An.…”